1. Field of the Invention
This invention relates to radio frequency identification, more particularly, articles containing chipless radio frequency identification elements.
2. Discussion of the Art
Currently, in the area of medical diagnostics, identification of containers is generally effected by bar code labels. Bar code labels require printing onto or application onto the surface of the container. Bar code labels require an unobstructed optical path to be read, which generates design challenges for both the container and the bar code readers. The bar code label is required to be clear, i.e., the print quality must be satisfactory and the label must be clear of foreign material, such as frost resulting from humidity and storage at low temperatures. Bar code labels generally have only a limited quantity of space, with the result that the information that can be written on a bar code label is extremely limited. Bar code labels can be removed and reused, thereby leading to counterfeiting issues. Bar code labels can delaminate from the containers on account of condensation of water or low temperatures.
In the area of medical diagnostics, identification of containers by means of radio frequency identification tags and data capturing systems utilizing radio frequency identification tags can be used in order to comply with Food and Drug Administration (FDA) regulations for management of supply chains.
Radio frequency identification tags can be categorized as active, semi-passive, and passive radio frequency identification tags. The main difference between the three types of radio frequency identification tags resides in the nature of the power supply. The passive radio frequency identification tag does not require any installed power source. The passive radio frequency identification tags contain a microchip and an antenna. The minute electrical current induced in the antenna by an incoming radio frequency signal provides sufficient power to cause the microchip to transmit a response. FIG. 1 illustrates a typical radio frequency identification tag that has a microchip and an antenna.
Currently available radio frequency identification tags are not suitable for common diagnostic products on account of size and orientation requirements. Containers for diagnostic reagents and other disposable products are often small in size. The size of a radio frequency identification tag is limited by the size of the antenna. A commercially available radio frequency identification tag manufactured by Avery Dennison is as small as 1 inch by 1 inch. The liquid contained in reagent containers and metal in proximity to reagent containers can cause interference with radio frequency signals. Signal receiving and backscattering are dependent upon direction; accordingly, the placement of radio frequency identification tags on an object is critical. The most critical obstacle for utilizing radio frequency identification tags is high cost. The cost of microchips associated with radio frequency identification tags is high relative to the cost of typical diagnostic products.
Microchips are expensive, unless they can be mass-produced. Finally, the scrap rate of radio frequency identification tag assembly is high on account of the difficulty inherent in the placement of a chip on the antenna contacts. U.S. patent application Ser. No. 2006/0202830 discloses a blister package with an integrated radio frequency identification tag. The conductive lidding material is modified to serve not only to seal some contents within some formed blister film, but also to act as a radio frequency identification antenna. An integrated circuit chip is electrically connected to the lidding film antenna. This patent also discloses methods for making such blister packages. This disclosure is limited to attaching a radio frequency identification tag to a film.
U.S. patent application Ser. No. 2006/0030049 discloses a method of placing in a diagnostic system at least one cartridge containing a reservoir of reagent and carrying an identifier device that has information pertinent to the reagent in the reservoir. The diagnostic system automatically reads the information contained in the identifier device and used the information to control the diagnostic system in dispensing the reagent. The information contained in the device may consist of one or more of an identification of the reagent in the reservoir; the expiration date of the reagent; the active shelf life of the reagent; the volume of the reagent in the reservoir; an identification of the origin of the reagent; and the maximum storage temperature of the reagent. Iris Diagnostics integrates an authentication system based on radio frequency identification into the iQ200 Urinalysis system.
U.S. Pat. No. 5,381,137 discloses a system utilizing radio frequency identification tags having a plurality of resonant circuits. When the radio frequency identification tag enters a detection zone, the system determines the resonant frequency of each of the resonant circuits and produces a corresponding code that identifies a tagged article. This system requires a plurality of circuits to be built into a radio frequency identification tag, which increases the manufacturing cost. Special focused beam antennas are preferred to locate the individual resonant circuits on the radio frequency identification tag. The complexity of the system causes this system to be costly.
U.S. Pat. No. 7,075,434 discloses a method for encoding a radio frequency identification tag with an n-bit binary code. One or more predetermined frequency sources are associated with the radio frequency identification tag. The radio frequency identification tag produces known different respective characteristic frequencies, each of which is associated with a known unique position in the n-bit binary code. The patent fails to disclose how to resolve the detected multiple frequencies and method of matching the corresponding code. The decoding process relies upon band-pass filters to identify multiple frequency resonant elements. The band-pass filter approach cannot differentiate those resonant elements that have small differences in their resonant frequencies. The scattering approach of the detection is limited to higher frequency ranges (915 MHz and 2.45 GHz).
U.S. patent application Ser. No. 2007/0005367 describes a scattering agent attached to an object to provide a reproducible radio frequency fingerprint that can be used to authenticate a tag or seal for the object. The radio frequency fingerprint is measured and digitized, combined with information associated with the object to which a radio frequency certificate of authenticity is attached, and stored in a radio frequency identification system associated with the radio frequency certificate of authenticity. A scanner receives the fingerprint and the information and authenticates the information by comparing the fingerprint against a new fingerprint obtained from the object. Only one category of scattering agent is used and a three-dimensional arrangement is relied on to generate a fingerprint. The cost of generating a database for later authentication is expensive.
U.S. Pat. Nos. 7,180,304; 7,205,774; and 7,221,168 disclose microwave readable barcode formed from a pattern of dielectric material printed on the surface of an article. The barcodes need to be printed and are subject to wear and alteration.
U.S. Pat. Nos. 6,708,881 and 6,966,493 disclose surface acoustic wave identification tags and methods of operating and identifying the tag. The tag includes (1) a piezoelectric substrate having a surface acoustic wave transducer located thereon, (2) a group of slots arranged by both pulse position and phase position on the substrate; and (3) a number of reflectors distributed among the slots such that the reflectors encode a number by both pulse position and phase position. The tag is made of a piezoelectric material. The manufacturing cost for the disclosed features is high.
U.S. Pat. No. 6,997,388 discloses radio frequency data carrier having at least one diffraction element. The radio frequency data carrier comprises at least one diffraction element that has a dimension of the order of a wavelength of radio frequency radiation and is responsive to radio frequency irradiation, the response produced by the diffraction elements in the data carrier being indicative of machine-readable data carried by the data carrier. The diffraction element can be incorporated into an article. No decoding feature is mentioned.
It would be desirable to have a product identification system that is a more versatile than a conventional barcode system. It would also be desirable to have a radio frequency identification system that can be prepared by an inexpensive method.